1. Field of Invention
This invention relates generally to cable protectors for earth moving vehicles and more particularly to portable cable crossovers of high strength resinous material to withstand high tonnage loads of earth moving vehicles such as those used in open pit mining. The present invention is intended especially for use with electric cables required to furnish power to electrically operated excavating machinery used in strip mining and other similar large scale earth moving operations such that the crossover shields the cable from damage due to ground-engaging earth moving loads of many tons, e.g. 200 tons which traverse the crossover.
2. Prior Art
In large scale strip mining operations, it is common practice to use electrically powered excavating machines, all supplied with electrical energy from one or more primary sources. In this regard, a serious problem has been encountered in communicating the electricity from the source to the excavating machine and at the same time providing access for high tonnage earth moving vehicles between the excavating machine where the vehicles are loaded with earth, and a suitable dump site. One proposed solution has been to use temporary power poles which engage the ground at one end and form a bridge between which the cable spans at an elevation substantially above the ground. The elevations to which such poles must extend are substantial since the earth moving vehicles in question extend above the ground on the order of 20-25 feet. Consequently, if the poles are not imbedded in the ground, wind and other forces of nature frequently cause them to fall to the ground decreasing the efficiency of the mining operation and risking property damage and personal injury frequently caused when a high tonnage earth moving vehicle runs directly across an electric cable of the type needed for the mentioned excavating machinery. On the other hand, any installation of the type mentioned, is temporary since excavation sites vary rather rapidly. Hence, it is uneconomical to anchor one end of the power poles into the ground to the extent necessary to resist loads imposed by nature. In addition, it has been found that earth moving vehicles commonly strikes such poles. It has also been proposed that the required electric cable be placed upon the ground and shielded by high strength metal crossovers in one fashion or another. This approach has proved disadvantageous since the high tonnage earth moving vehicles tend to impose their load along two narrow areas of the metal crossovers causing them to curl or bow. Thereafter, continued use of curled or bowed steel crossovers poses an undue hazard to equipment and personnel.